SOLVENT EXTRACTION CHEMISTRY: A FEW THOUGHTS ABOUT ITS INTERDISCIPLINARY NATURE,CHALLENGES AND OPPORTUNITIES

Abstract

In this article, the results of the application of a boron removal treatment based on a process of chemosorption on liquid waste of urban, agricultural, or industrial origin is presented. The isotherms of the process have been established and a study of the influence of the different variables in the tests in columns has been carried out. The results obtained indicate that the process of chemosorption shows strongly favorable isotherms, and moreover it is notably influenced by the variable “flow rate,” making the breakthrough point appear earlier and the curves move towards the left. However, important differences in the curves for the variable “dimensions of the bed” have not been observed. Furthermore, a pH‐dependent mechanism for the treatment process of boronated effluents by means of chemosorption with the specific Amberlite IRA-743 resin was developed. According to breakthrough point data, experimentally achieved in elution tests for the maximum value allowed by environmental legislation, of 3 mg B L^?1, a double mechanism is proposed. It can be suggested that for basic pH the mechanism corresponds to stereospecific reactivity between the borate ion and hydroxide groups of the N‐methylglucamine active site of the resin in cis‐position, a maximum appearing between pH 8.5 and 9.5, corresponding to borate ion predominance. On the other hand, a mechanism based on the hydrogen bridge bond formation reaction between the ionized amino group of the resin and boric acid is suggested for neutral and slightly acid pH. This last reaction differentiates this resin from the other absorbents used for boron removal in industrial wastes, such as metallic oxides, clays, humic acids, and so on.